This application is for support as one of the participating centers in the Cooperative Study of Drugs and Coronary Heart Disease. The primary objective of this proposal is to supply to the Coronary Drug Project reliable ECG indices of new cardiac events related to Coronary Heart Disease. Secondary goals are to augment the diagnostic and predictive power of the ECG by a quantitative assessment of the significance of change over time in the ECG, and to describe the natural course of coronary artery disease. This is a continuing requirement for the Coronary Drug Project through February of 1975. If the CDPA (Coronary Drug Project Aspirin study) continues through 1975 it will have the same needs as the Coronary Drug Project.